NGC 7331 (also known as Caldwell 30) is a spiral galaxy about 40 megalight-years away in the constellation Pegasus. It was discovered by William Herschel in 1784. NGC 7331 is the brightest member of the NGC 7331 Group of galaxies.

It has been believed that the galaxy is similar in size and structure to the galaxy we inhabit, and is often referred to as "the Milky Way's twin", although recent discoveries regarding the structure of the Milky Way may call this similarity into doubt.

In spiral galaxies the central bulge typically co-rotates with the disk but the bulge in the galaxy NGC 7331 is rotating in the opposite direction to the rest of the disk. The current bulge may have formed from infalling material, however if it has been there since the formation of the galaxy then it would be difficult to explain how such a situation arose. [Source: Wikipedia]

The background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away. Their close alignment on the sky with NGC 7331 occurs just by chance. Seen here through faint foreground dust clouds lingering above the plane of Milky Way, this visual grouping of galaxies is also known as the Deer Lick Group. [Source: APOD]

NGC 7331 is one of 18 galaxies chosen by the HST Extragalactic Distance Scale Key Project to calibrate secondary distance estimators. The project will use the Hubble Space Telescope to obtain an accurate distance to galaxies via Cepheid variables, with the ultimate goal of using these to measure H0 (a cosmological parameter) to an external accuracy of 10%. It was determined this galaxy is 49 million light years away- and perhaps 30,000 light years across (note distance dis-agreement with Wikipedia). In this image you will see some of the nearby neighbors being both spiral and elliptical galaxies. Nearby this field (not shown) is another famous group of galaxies known as Stephan's Quintet. [Source: Best of AOP]

The image was captured with the Meade 12"LX200, using the Atik 383L+ mono at F7.16. Astronomik's LRGB filters were used. All subs were taken at 1x1 bin, -10C, and 10 minutes each.

Image:

Lum : 50 subs (8.33hr) on Oct 14th, 17th and 19th.

Red : 10 subs (1.67 hr) on Oct 15th.

Green : 10 subs (1.67 hr) on Oct 17th.

Blue : 11 subs (1.83 hr) on Oct 17th and 18th.

Processing was done with PixInsight, following (for the most part) kayronjm's tutorial of Feb. 24th. Only L was used to develop the Luminance image. R, G and B were collected for the color mix.

North is up, and this is a very slight crop. This is about my fourth full use of the Plate Solve capability within Sequence Generator Pro (using Astrometry), and I am extremely pleased with it.

Until proven differently, I'm continuing to blame the light pollution for the RGB gradient. I can get some of the gradient out, but not all. Nevertheless, it's a pretty decent main galaxy and the lessor ones are interesting.